Coaxial nanotubes of stimuli responsive polymers with tunable release kinetics

Controlled Release Utilizing Initiated Chemical Vapor Deposited (iCVD) of Polymeric Nanolayers

This review will focus on the controlled release of pharmaceuticals and other organic molecules utilizing polymeric nanolayers grown by initiated chemical vapor deposited (iCVD). The iCVD layers are able conform to the geometry of the underlying substrate, facilitating release from one- and two-dimensional nanostructures with high surface area. The reactors for iCVD film growth can be customized for specific substrate geometries and scaled to large overall dimensions. The absence of surface tension in vapor deposition processes allows the synthesis of pinhole-free layers, even for iCVD layers <10 nm thick. Such ultrathin layers also provide rapid transport of the drug across the polymeric layer. The mild conditions of the iCVD process avoid damage to the drug which is being encapsulated. Smart release is enabled by iCVD hydrogels which are responsive to pH, temperature, or light. Biodegradable iCVD layers have also be demonstrated for drug release.

The toolbox of porous anodic aluminum oxide–based nanocomposites: from preparation to application

Anodic aluminum oxide (AAO) templates have been intensively investigated during the past decades and have meanwhile been widely applied through both sacrificial and non-sacrificial pathways. In numerous non-sacrificial applications, the AAO membrane is maintained as part of the obtained composite materials; hence, the template structure and topography determine to a great extent the potential applications. Through-hole isotropic AAO features nanochannels that promote transfer of matter, while anisotropic AAO with barrier layer exhibits nanocavities suitable as independent and homogenous containers. By combining the two kinds of AAO membranes with diverse organic and inorganic materials through physical interactions or chemical bonds, AAO composites are designed and applied in versatile fields such as catalysis, drug release platform, separation membrane, optical appliances, sensors, cell culture, energy, and electronic devices. Therefore, within this review, a perspective on exhilarating prospect for complementary advancement on AAO composites both in preparation and application is provided.

Vapor-deposited functional polymer thin films in biological applications

Functional polymer coatings have become ubiquitous in biological applications, ranging from biomaterials and drug delivery to manufacturing-scale separation of biomolecules using functional membranes. Recent advances in the technology of chemical vapor deposition (CVD) have enabled precise control of the polymer chemistry, coating thickness, and conformality. That comprehensive control of surface properties has been used to elicit desirable interactions at the interface between synthetic materials and living organisms, making vapor-deposited functional polymers uniquely suitable for biological applications. This review captures the recent technological development in vapor-deposited functional polymer coatings, highlighting their biological applications, including membrane-based bio-separations, biosensing and bio-MEMS, drug delivery, and tissue engineering. The conformal nature of vapor-deposited coatings ensures uniform coverage over micro- and nano-structured surfaces, allowing the independent optimization of surface and bulk properties. The substrate-independence of CVD techniques enables facile transfer of surface characteristics among different applications. The vapor-deposited functional polymer thin films tend to be biocompatible because they are free of remnant toxic solvents and precursor molecules, potentially lowering the barrier to clinical success.

Electrospun Nanofibers With pH-Responsive Coatings for Control of Release Kinetics

Functional and stimuli-responsive nanofibers with an enhanced surface area/volume ratio provide controlled and triggered drug release with higher efficacy. In this study, chemotherapeutic agent Rose Bengal (RB) (4,5,6,7-tetrachloro-2', 4',5',7'-tetraiodofluoresceindisodium)-loaded water-soluble polyvinyl alcohol (PVA) nanofibers were synthesized by using the electrospinning method. A thin layer of poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) p(4VP-co-EGDMA) was deposited on the RB-loaded nanofibers (PVA-RB) via initiated chemical vapor deposition (iCVD), coating the fiber surfaces to provide controllable solubility and pH response to the nanofibers. The uncoated and [p(4VP-co-EGDMA)-PVA] coated PVA-RB nanofiber mats were studied at different pH values to analyze their degradation and drug release profiles. The coated nanofibers demonstrated high stability at neutral and basic pH values for long incubation durations of 72 h, whereas the uncoated nanofibers dissolved in <2 h. The drug release studies showed that the RB release from coated PVA-RB nanofibers was higher at neutral and basic pH values, and proportional to the pH of the solution, whereas the degradation and RB release rates from the uncoated PVA-RB nanofibers were significantly higher and did not depend on the pH of environment. Further analysis of the release kinetics using the Peppas model showed that while polymer swelling and dissolution were the dominant mechanisms for the uncoated nanofibers, for the coated nanofibers, Fickian diffusion was the dominant release mechanism. The biocompatibility and therapeutic efficiency of the coated PVA-RB nanofibers against brain cancer was investigated on glioblastoma multiforme cancer cells (U87MG). The coated PVA nanofibers were observed to be highly biocompatible, and they significantly stimulated the ROS production in cells, increasing apoptosis. These promising results confirmed the therapeutic activity of the coated PVA-RB nanofibers on brain cancer cells, and encouraged their further evaluation as drug carrier structures in brain cancer treatment.

Multifunctional one-dimensional polymeric nanostructures for drug delivery and biosensor applications

Advances in nanotechnology in the last decades have paved the way for significant achievements in diagnosis and treatment of various diseases. Different types of functional nanostructures have been explored and utilized as tools for addressing the challenges in detection or treatment of diseases. In particular, one-dimensional nanostructures hold great promise in theranostic applications due to their increased surface area-to-volume ratios, which allow better targeting, increased loading capacity and improved sensitivity to biomolecules. Stable polymeric nanostructures that are stimuli-responsive, biocompatible and biodegradable are especially preferred for bioapplications. In this review, different synthesis techniques of polymeric one-dimensional nanostructures are explored and functionalization methods of these nanostructures for specific applications are explained. Biosensing and drug delibiovery applications of these nanostructures are presented in detail.